For cardiovascular epidemiology, a classification code for 12-lead electrocardiograms (ECG's) was developed by H. Blackburn et al. which is based on objective, manual measurements, avoiding controversial clinical interpretations. The grading, in terms of increasing abnormality, based on clinical ECG criteria accepted at that time. The coding can be done satisfactorily by non-medical personnel. This "Minnesota Code" has been accepted internationally for cardiovascular epidemiological studies and clinical screening. The Frank-lead system with three orthogonal X,Y,Z leads is being used increasingly, replacing the conventional ECG. This "corrected" system has reduced the electrical distortion inherent in conventional leads and the redundancy of information, thus improving the accuracy of measurements and statistical evaluation. In view of increasing application of Frank leads, development of a classification code for this lead system is necessary. This code will be superior to the Minnesota Code; i.e., the constitutional variables (sex, age, weight, and race) which affect the ECG will be considered, and instead of the arbitrary grading in the Minnesota Code, the grading will be based on actual frequency distributions (percentile) of the various selected ECG items in large samples of normals and abnormals. Alternatively, the likelihood ratio, which has provided the theoretical basis for the multivariate computer analysis of the ECG, will also be given careful consideration. For simplicity the code will be based on scalar ECG items. Data will be obtained by means of electronic computers but will be designed for manual measurements. It is expected that the proposed code will facilitate the epidemiological studies and clinical screening of cardiovascular diseases.